AP: No doubt there is much material in the Gospels that is impossible to judge with certainty whether it belongs to the historical stratum closest to Jesus or actually a product of a later re-elaboration of the primitive tradition or of the Gospels themselves. And if you do not have solid material then it is difficult, or even impossible, to build a "life" of Jesus upon them. For this reason several researchers have turned their eyes towards another system, something known as "recurrent attestation."
I think I have already defined what this is in one of previous posts, but I will do so again, but briefly. According to Bermejo, who gathers ideas already initiated by researchers of the early twentieth century, recurrent attestation is when Gospel texts point to the same direction, passages, or sentences that, when taken together, produce a vision of the whole and transmit a solid representation of an attitude of Jesus or a fact about his life or his being. And he puts forth the following example: If the Gospels are read well, there are enough passages or brief allusions that point to the idea that Jesus had a high awareness of himself and his mission. It is not always possible to have guarantees of authenticity about each particular text, but the recurrent presence of the same idea in the sources allows the researcher to arrive at a certain degree of certainty.
Bermejo enthusiastically welcomes this method and I agree with him that it is very helpful. And I'm going to allow myself to quote it again because this system of investigating Jesus is older than it seems and has been used by investigators with a sort of confessional slant, though without calling it by its current name. This is the case of C. H. Dodd, whose ideas about the Fourth Gospel––which gives a joint historicity that other scholars deny––are always interesting.
The example is this: If a group is formed, a cluster of the following passages, one can arrive at the very plausibly historical conclusion that Jesus had an open attitude toward the marginalized of the society in which he lived and that he paid them much attention as potential candidates to enter the kingdom of God, whose coming he preached:
1. The call of Levi to the apostolate (Mark 2:14).
2. The festival with publicans and sinners (Mark 2:15–17).
3. The episode of Zacchaeus (Luke 19: 2–10).
4. A sinner in the house of Simon (Luke 7:36–48).
5. The pericope of the adulteress (John 7:53–8:11).
6. The parable of the lost sheep (Luke 15:4–7; Matt. 18:12–13).
7. The parable of the Pharisee and the publican (Luke 18:10–14).
8. The parable of the children in the market (Matt. 11:16–19; Luke 7:31–35).
9. Jesus' teaching about publicans and prostitutes who enter the Kingdom (Matt. 21:32).Bermejo comments: "We have here material extracted from a great variety of sources and forms. Although individual incidents are rarely repeated, the general reason does. And C. H. Dodd concludes that the idea that Jesus showed an open attitude towards the marginalized corresponds to the historical reality."
I also add to this proposal, and I think it is a good system to build "patterns" in which to frame Jesus with certain certainty. And once a solid framework of interpretation has been constructed, other dubious materials may be added by the criterion of coherence.
An example: If the analysis of the texts that relate John the Baptist to Jesus (apart from the thorny case of whether the Baptist was Jesus' teacher or simply his precursor) and the observation that parts of the Baptist's preaching is collected and repeated by Jesus in the three Synoptic Gospels (Mark, Matthew, and Luke), we can conclude with some certainty that, at least at the beginning of his ministry, the mental frame of the Nazarene and his preaching was that of the traditional apocalyptic Jewish thought of his time. And by the criterion of coherence, and although some of the texts are doubtful in themselves as to their attribution to Jesus and not to their disciples or to an author of a Gospel, We can suppose that the apocalyptic material of the great eschatological discourse of Mark 13––I insist, although he could not be entirely traced back to Jesus––did correspond in general to his tone and mental frame: Jesus was a Jewish apocalyptic prophet. The method has notable consequences, as it will point to a fundamentally Jewish Jesus who did not break the mental frames of his religion. It will be implausible according to the historical odds that Jesus has overcome Judaism, leaving it obsolete.